Zero-valent Iron Catalyze Hydrogen Peroxide And Sodium Persulfate Fenton-like Degrada Reactive Brilliant Orange X-GN

As a public known refractory industrial wastewater,dyeing wastewater contains complex pollutant,alkalinity,color and high amount of organic compounds and it is not biodegradable.With the development of technology,finishing agent and new additives were used in printing and dyeing industry widely.It is necessary that to treat the dyeing wastewater efficiently.Fenton technology originates from 19 th centry and it is applied in treatment of wastewaters widely.However,the application of Fenton technology is limited by narrow reaction pH range,low Fe2+ utilization efficiency,large amount ferrous salts and iron-containing sludge.In order to overcome the limitations above and improve the Fenton technology,this study replaces Fe2+ and H₂O₂ with Fe⁰ and Na₂S₂O₈ to build a novel heterogeneous Fenton system to degrade dyeing wastewater.Fe⁰/H₂O₂ hetergeneous Fenton system was built to degrade the azo dye reactive brilliant orange X-GN,this study investigates the effect of initial pH,the dosage of H₂O₂ and Fe⁰ and the reaction temperature on the X-GN removal.The iron leaching concentration after the reacton is investigated as well.The results show that Fe⁰/H₂O₂ hetergeneous Fenton system degrade the X-GN effectively with lower production of iron-containing sludge.When the initial X-GN concentration is 100 mg/L,initial pH is 3,Fe⁰ dosage is 1 g/L,H₂O₂ dosage is 5 mmol/L and reaction temperature is 30 oC,the X-GN removal efficiency is above 95% after 60 min reaction time,and the iron concentration after the reaction is lower than 1 mg/L.The UV-vis spectra analysis shows that the chromophoric group and benzene structure were destroyed during the Fenton reaction.However,the Fe⁰/H₂O₂ hetergeneous Fenton system is limited by the initial pH.When the initial pH is 3,the X-GN removal efficiency is 2.5,5 and 15 fold of the efficiency of the systems when the initial pH is 6,8 and 10,respectively.Fe⁰/Na₂S₂O₈ hetergeneous Fenton system was built to degrade the azo dye reactive brilliant orange X-GN,this study investigates the effect of initial pH,the dosage of Na₂S₂O₈ and Fe⁰ and the reaction temperature on the X-GN removal.The iron leaching concentration after the reacton is investigated as well.The results show that X-GN is degraded by Fe⁰/Na₂S₂O₈ hetergeneous Fenton system effectively.With comparison to the Fe⁰/H₂O₂ system,the leaching iron concentration of Fe⁰/Na₂S₂O₈ system is higher,but it is still lower than the traditional Fenton system.When the initial X-GN concentration is 100 mg/L,initial pH is 7,Fe⁰ dosage is 0.5 g/L,Na₂S₂O₈ dosage is 1 mmol/L and reaction temperature is 30 oC,the X-GN removal efficiency is above 92.6% after 60 min reaction time,and the iron concentration after the reaction is lower than 2.2 m g/L.The optimum pH range of Fe⁰/Na₂S₂O₈ system is broader than Fe⁰/H₂O₂ system.When the initial pH is between 2 and 9,the initial X-GN concentration is 100 mg/L,Fe⁰ dosage is 0.5 g /L,Na₂S₂O₈ dosage is 1 mmol/L and reaction temperature is 30 oC,the X-GN removal efficiency is higher than 90% after 60 min reaction time.The effect of Fe⁰ dosage on t he X-GN removal efficiency of Fe⁰/Na₂S₂O₈ system is not significant,and the Fe⁰ dosage is easy to control.When the X-GN concentration is 100 mg/L,initial pH is 7,Fe⁰ dosage range from 0.1 to 2 g/L,the Na₂S₂O₈ dosage is 1 mmol/L,and the reaciton temperature is 30 oC,the X-GN removal efficiency is higher than 86.8% after 60 min reaciton time.Consider all the description above,Fe⁰/Na₂S₂O₈ system can degrade X-GN effectively with a broad optimum pH range and low leaching iron concentration,and this system is not affected significantly by the Fe⁰ dosage.It is a promising wastewater treatment technology.